A variety of powered toy hand drawing devices for marking patterns have been proposed over many years for amusement and decorating purposes.
U.S. Pat. No. 3,297,003 issued to Benson in 1967, teaches one type of powered toy hand drawing device comprising an elongate, manually grippable, pen-receiving casing or barrel having an open, writing end; rotary drive means mounted to an opposite end; and means for movably supporting a pen within the barrel with a writing tip of the pen protruding from the writing end and an opposite end of the pen eccentrically driven by the rotary drive means and, fulcrum means encircling the pen at a location between the opposite end and the writing end so that operation of the rotary drive means produces oscillation or circular movement of the writing tip, enabling looping or helical patterns to be drawn by moving the writing tip across a writing surface.
A disadvantage of the known device is that, as a consequence of the fulcrum means being constituted by a fixed constriction in the wall of the casing or barrel, the amplitude of movement of the writing tip can only be altered by changing a tip confining end piece mounted on the open end of the casing. In the absence of the end piece, circles described by the tip will all be of the same size.
An additional disadvantage of the prior device follows from the requirement for the body of the pen to directly engage the drive means and the fulcrum means apparently limiting use to a single type of pen precisely matched in length and cross-section.
U.S. Pat. No. 4,835,874 issued in 1989 to Ellman teaches a powered toy hand drawing device which relies on the forces from an eccentric mass mechanism to produce periodic motion while the user's fingers provide a a fulcrum means with consequential difficulties in control.
Other examples of powered toy hand drawing devices are taught by U.S. Pat. No. 3,390,460 issued in 1968 to Brown; U.S. Pat. No. 5,433,642 issued in 1995 to Chia; U.S. Pat. No. 3,997,972 issued in 1976 to Jaunarais.
U.S. Pat. No. 3,861,077 issued in 1975 to Lindquist teaches a toy marking device constituted by a spinning top and U.S. Pat. No. 4,419,041 issued in 1993 to Rose teaches a relatively complex spacial mechanism for replacing articulated arm structures of robotic devices.